Before abruptly leaving his Zoom news conference Tuesday morning, Mike Zimmer expressed optimism that his team will bounce back from his worst season as a head coach.

Which is what you would expect. Zimmer is facing a prove-it season in 2021. He has little choice but to find reasons for hope, and some of his hopes are realistic.

Yes, getting Danielle Hunter, Michael Pierce and Anthony Barr back, and getting Eric Kendricks through a full season in good health would fix much of what was wrong with his defense.

Yes, the Vikings' offense played well this season.

But there are reasons to temper this forced optimism:

• Assuming that everything that went well in 2020 will go well in 2021 is naive.

• Assuming that every player will return from injury or an opt-out at their previous level of play is risky.

• Assuming that the Vikings will have enough salary cap space to shore up their weaknesses and keep all of their key players may be foolish.

• Zimmer might have to find himself a new offensive coordinator and kicker, two positions that have plagued him periodically.

• Even in good years, the Vikings rarely win at Lambeau Field and Soldier Field. They made it to seven victories in 2020 with those two victories and by taking advantage of an easy schedule.

Next year they will have to play the Seahawks, Rams, Cardinals, Steelers, Browns and Ravens, plus the Bengals, Panthers and Cowboys, and the Cowboys should have Dak Prescott back.

The 2020 Vikings were devastated by defensive injuries. On offense, they enjoyed career or exceptional years from Kirk Cousins, Dalvin Cook and Justin Jefferson, and highly productive seasons from Adam Thielen, Riley Reiff, Brian O'Neill and Garrett Bradbury.

Cousins, Jefferson, Reiff, O'Neill and Bradbury played every game with the exception of Reiff missing the meaningless finale while in COVID protocol. Cook missed only one meaningful game despite amassing 356 touches, 53 more than his previous career high. Thielen, who will be 31 next season, missed just one game.

Assuming better defensive health is fair. But so is assuming less good fortune in terms of offensive health, which is worrisome because of the Vikings' lack of quality depth at wide receiver, offensive line and quarterback.

Reiff will cost more than $11 million against what could be a reduced salary cap in 2021. The Vikings can't afford to let him go. They also might not be able to afford to keep him.

Pierce was signed to shore up the middle of the Vikings' defensive line. Will he be the player the Vikings need him to be after spending a year away from football?

The Vikings' most immediate concern should be the upcoming decision of offensive coordinator Gary Kubiak, who is considering retirement. Zimmer wants a veteran, old-school offensive coordinator who values running the ball. Kubiak was ideal, as was Pat Shurmur.

Zimmer has sparred with at least two of his offensive coordinators — Norv Turner and John DeFilippo.

If he needs to hire a new coordinator, he probably will look for someone like Kubiak or Shurmur, but how many old-school coaches who fit Zimmer's preferences and personality are there?

He could do far worse than hiring Anthony Lynn, who was just fired by the Chargers despite helping Justin Herbert to a record-setting rookie season.

Zimmer also has been tough on kickers. If he keeps Dan Bailey, the entire franchise will remember Tampa every time Bailey lines up in a close game. If he ditches Bailey, he will again be looking for someone like Daniel Carlson, whom he cut in 2018.

What's most interesting about Zimmer's tenure and approach is that his high-water mark arrived in 2017, when his defense was at its best and Shurmur coaxed career seasons out of Case Keenum and Jerick McKinnon.

That team won 13 regular-season games. Then the Vikings signed Cousins. They have averaged 8.3 victories per season since. In the three seasons before Cousins arrived, the Vikings won an average of 10.7.

So perhaps the right level of optimism for this coach and team is expecting the Vikings to get back to 8-to-10 victories, so they can fight for second place in the NFC North.

Jim Souhan's podcast can be heard at TalkNorth.com. On Twitter: @SouhanStrib. • jsouhan@startribune.com